在现代浏览器中，您可以使用regexp和unicode属性测试。

/\p{Lu}/u.test("A") // is true
/\p{Lu}/u.test("Å") // is true
/\p{Lu}/u.test("a1å") // is false

更多信息:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions/Unicode_Property_Escapes

一般类别列表如下:

https://unicode.org/reports/tr18/#General_Category_Property

Stephen Nelsons的函数转换成带有大量测试示例的原型。

为了完整起见，我还在函数中添加了整个字符串。

有关其他注释，请参阅代码。

/* Please note, there's no requirement to trim any leading or trailing white spaces. This will remove any digits in the whole string example returning the correct result. */ String.prototype.isUpperCase = function(arg) { var re = new RegExp('\\s*\\d+\\s*', 'g'); if (arg.wholeString) {return this.replace(re, '') == this.replace(re, '').toUpperCase()} else return !!this && this != this.toLocaleLowerCase(); } console.log('\r\nString.prototype.isUpperCase, whole string examples'); console.log(' DDD is ' + ' DDD'.isUpperCase( { wholeString:true } )); console.log('9 is ' + '9'.isUpperCase( { wholeString:true } )); console.log('Aa is ' + 'Aa'.isUpperCase( { wholeString:true } )); console.log('DDD 9 is ' + 'DDD 9'.isUpperCase( { wholeString:true } )); console.log('DDD is ' + 'DDD'.isUpperCase( { wholeString:true } )); console.log('Dll is ' + 'Dll'.isUpperCase( { wholeString:true } )); console.log('ll is ' + 'll'.isUpperCase( { wholeString:true } )); console.log('\r\nString.prototype.isUpperCase, non-whole string examples, will only string on a .charAt(n) basis. Defaults to the first character'); console.log(' DDD is ' + ' DDD'.isUpperCase( { wholeString:false } )); console.log('9 is ' + '9'.isUpperCase( { wholeString:false } )); console.log('Aa is ' + 'Aa'.isUpperCase( { wholeString:false } )); console.log('DDD 9 is ' + 'DDD 9'.isUpperCase( { wholeString:false } )); console.log('DDD is ' + 'DDD'.isUpperCase( { wholeString:false } )); console.log('Dll is ' + 'Dll'.isUpperCase( { wholeString:false } )); console.log('ll is ' + 'll'.isUpperCase( { wholeString:false } )); console.log('\r\nString.prototype.isUpperCase, single character examples'); console.log('BLUE CURAÇAO'.charAt(9) + ' is ' + 'BLUE CURAÇAO'.charAt(9).isUpperCase( { wholeString:false } )); console.log('9 is ' + '9'.isUpperCase( { wholeString:false } )); console.log('_ is ' + '_'.isUpperCase( { wholeString:false } )); console.log('A is ' + 'A'.isUpperCase( { wholeString:false } )); console.log('d is ' + 'd'.isUpperCase( { wholeString:false } )); console.log('E is ' + 'E'.isUpperCase( { wholeString:false } )); console.log('À is ' + 'À'.isUpperCase( { wholeString:false } )); console.log('É is ' + 'É'.isUpperCase( { wholeString:false } )); console.log('Ñ is ' + 'Ñ'.isUpperCase( { wholeString:false } )); console.log('ñ is ' + 'ñ'.isUpperCase( { wholeString:false } )); console.log('Þ is ' + 'Þ'.isUpperCase( { wholeString:false } )); console.log('Ͻ is ' + 'Ͻ'.isUpperCase( { wholeString:false } )); console.log('Ͽ is ' + 'Ͽ'.isUpperCase( { wholeString:false } )); console.log('Ά is ' + 'Ά'.isUpperCase( { wholeString:false } )); console.log('Έ is ' + 'Έ'.isUpperCase( { wholeString:false } )); console.log('ϴ is ' + 'ϴ'.isUpperCase( { wholeString:false } )); console.log('Ϋ is ' + 'Ϋ'.isUpperCase( { wholeString:false } )); console.log('Ϣ is ' + 'Ϣ'.isUpperCase( { wholeString:false } )); console.log('Ϥ is ' + 'Ϥ'.isUpperCase( { wholeString:false } )); console.log('Ϧ is ' + 'Ϧ'.isUpperCase( { wholeString:false } )); console.log('Ϩ is ' + 'Ϩ'.isUpperCase( { wholeString:false } )); console.log('Ϫ is ' + 'Ϫ'.isUpperCase( { wholeString:false } )); console.log('Ϭ is ' + 'Ϭ'.isUpperCase( { wholeString:false } )); console.log('Ϯ is ' + 'Ϯ'.isUpperCase( { wholeString:false } )); console.log('Ϲ is ' + 'Ϲ'.isUpperCase( { wholeString:false } )); console.log('Ϸ is ' + 'Ϸ'.isUpperCase( { wholeString:false } )); console.log('Ϻ is ' + 'Ϻ'.isUpperCase( { wholeString:false } ));

我相信这是最简单的解决办法。你可以在输入字段中使用onchange处理程序。进行验证

const isValid = e.target.value === e.target.value.toLowerCase()

if (isValid) {
  //Do something
} else {
  //Do something
}

你可以使用正则表达式测试和toUpperCase方法:

String.prototype.charAtIsUpper = function (atpos){
      var chr = this.charAt(atpos);
      return /[A-Z]|[\u0080-\u024F]/.test(chr) && chr === chr.toUpperCase();
};
// usage (note: character position is zero based)
'hi There'.charAtIsUpper(3);      //=> true
'BLUE CURAÇAO'.charAtIsUpper(9);  //=> true
'Hello, World!'.charAtIsUpper(5); //=> false

另请参阅

我需要测试任何字符的字符串(包括空白，标记，数字，unicode字符…)因为空白、数字、标记……大写字母和小写字母都是一样的，我想找到真正的大写字母，我这样做:

let countUpperCase = 0;
let i = 0;
while (i <= string.length) {
  const character = string.charAt(i);
  if (character === character.toUpperCase() && character !== character.toLowerCase()) {
    countUpperCase++;
  }
  i++;
}

只需检查ASCII值

// IsLower verify that a string does not contains upper char
func IsLower(str string) bool {
    for i := range str {
        ascii := int(str[i])
        if ascii < 91 && ascii > 64 {
            return false
        }
    }
    return true
}